Drilling wells for various purposes is well-known. Such wells may be drilled for geothermal purposes, to produce hydrocarbons (e.g., oil and gas), to produce water, and so on. Well depth may range from a few thousand feet to 25,000 feet or more. In hydrocarbon wells, downhole tools often incorporate various sensors, instruments, and control devices in order to carry out any number of downhole operations. Downhole acoustic logging tools, which are used to investigate subsurface features, can include one or more acoustic transmitters or sources and a number of acoustic receivers. Additionally or alternatively, self-contained acoustic sensors may be installed within the borehole on either a temporary or permanent basis.
In some cases, the transmitters emit acoustic energy into the subsurface environment surrounding the wellbore. The acoustic signals are reflected by interfaces associated with the wellbore, well structures, and/or the formation. The reflected acoustic signals are detected by the receivers in the logging tool and processed to provide estimates of one or more properties of the wellbore, well structures, and/or the formation. Drilling systems having an acoustic “logging-while-drilling” (‘LWD’) or “measurement-while-drilling” (‘MWD’) system as part of a bottomhole assembly, or an after-drilling wireline logging system having an acoustic device for measuring properties of subsurface formations (during or after drilling of the wellbores), such as, for example, determining the location of formation bed boundaries around the bottomhole assembly, as in the MWD system, or around the wireline logging system are known.
In drilling a borehole to recover oil from the earth, it is often helpful to turn or steer the downhole drill bit toward or away from subterranean targets. Acoustic data may be used to determine a drill bit location on the seismic section to facilitate geosteering. With Vertical Seismic Profiling (VSP), acquisition may be conducted between one or more acoustic (seismic) sources on or near the surface of the earth, and receivers in the earth, such as, for example, in a wellbore. The response of an acoustic sensor, such as a seismic sensor (e.g., a hydrophone) at various depths in a borehole to sources on the surface may be recorded as downhole measurements.